Studied On Introduction And Drought Resistance Of Atriplex Canescens In Zhangye City

Atriplex canescens,belonging to Atriplex, family in Chenopodiaceae ,is good saline-sodic soil amelioration species.In this experiment, the growing condition and phonological period of Atriplex canescens was investigated.At the same time, the drought resistance of Atriplex canescens,comparing with Tamarix ramosissima and and Haloxylon ammodendron which are the local species was studied. The systematic provide theoretic direction and technical support in the fields of introduction.The thesis include two aspects :1 The growth condition investigation showed that: Atriplex canescens kept the high surviving rate and grew rapidly .The observation to phonological period showed that Atriplex canescens could grow in the introduction region.2 Studied on the drought resistance of Atriplex canescens,comparing with Tamarix ramosissima and Haloxylon ammodendron which are the local species.(1) Water condition : water content was gradually decreased with the drought stressed days increasing. The decrease of Atriplex canescens's water content was more than Haloxylon ammodendron. Haloxylon ammodendron could preserve water most efficiently.The relative water content showed the decrease of Atriplex canescens was more than Haloxylon ammodendron, but less than Tamarix ramosissima. Tamarix ramosissima and Haloxylon ammodendron kept more bond water than Atriplex canescens.(2) Protective enzymes activity: the activities of SOD,CAT,POD of three species had different change trend.SOD activity increased first,then decreased.The SOD activity of Tamarix ramosissima was always higher than Haloxylon ammodendron and Atriplex canescens .CAT activity increased immediately in the stressed period , and the increase of Tamarix ramosissima was much more than Haloxylon ammodendron and Atriplex canescens.These three species had different change tendency of POD activity.Tamarix ramosissima and Haloxylon ammodendron increased first,then decreased.But the POD acitivity of Atriplex canescens kept increasing,and it was higher than Tamarix ramosissima and Haloxylon ammodendron.(3) Osmoregulation matters:the proline content was increased in drought stressed course.The increasing rate of proline of Tamarix ramosissima was higher than that of Haloxylon ammodendron and Atriplex canescens.Soluble sugar and soluble protein of three species increased slowly.(4) Membrane injury:the content of MDA enhanced with the deeper of drought stressed, the degree of membrane injury of Atriplex canescens was deeper than Tamarix ramosissima and Haloxylon ammodendron. The membrane permeability of three species were increasing with the drought stress days. Atriplex canescens was higher injured to membrane system than others.(5) Chlorophyll content: there was a correlation between chlorophyll content and soil water content. The decrease of Chlorophyll content of Atriplex canescens was more than others.(6)Photosynthetic,transpiration,and water use efficiency:the three species all appeared middy depression,but the middy depression appeared at different time.The photosynthetic rates of Tamarix ramosissima and Atriplex canescens were higher than that of Haloxylon ammodendron all the day. The diurnal course of transpiration rate of three species appeared in curvilinear changes with singer peaks. The highest water use efficiency of three species all occurred in the morning.(7) Principal component analysis:it was considered that the information in first principal components of Tamarix ramosissima were water condition indices and the indices about the stability of plasmalemma,and the second principal component were protective enzymes and osmoregulation matters ; the information in first principal and second principal components of Haloxylon ammodendron were water condition indices and the indices about the stability of plasmalemma,and the third principal components were protective enzymes and osmoregulation matters; the information in first principal and second components of Atriplex canescens were protective enzymes,osmoregulation matters and the indices about the stability of plasmalemma,and the third principal components were water condition indices.This was different from Tamarix ramosissima and Haloxylon ammodendron.(8) By analyzing comprehensive appraisal of all physiological and biochemical indices, the results showed that the ability of drought resistance of three species were Haloxylon ammodendron>Tamarix ramosissima>Atriplex canescens. It was considered that three species were all having strong drought resistance ability.Atriplex canescens was introduced only a few years , so the drought resistance of Atriplex canescens was not as good as the local species.The problem need a further research in the future.